Does God exist? The universe had a start - what caused it?

Scientists are convinced that our Universe began with one enormous explosion of energy and light, which we now call the Big Bang. This was the singular start to everything that exists: the beginning of the universe, the start of space, and even the initial start of time itself.

Astrophysicist Robert Jastrow, a self-described agnostic, stated, "The seed of everything that has happened in the Universe was planted in that first instant; every star, every planet and every living creature in the Universe came into being as a result of events that were set in motion in the moment of the cosmic explosion...The Universe flashed into being, and we cannot find out what caused that to happen."9

Steven Weinberg, a Nobel laureate in Physics, said at the moment of this explosion, "the universe was about a hundred thousands million degrees Centigrade...and the universe was filled with light."10

The universe has not always existed. It had a start...what caused that? Scientists have no explanation for the sudden explosion of light and matter.